Computer systems and computer software are constantly evolving. As computer systems evolve, the computer software designed to run on them must also evolve. Often, systems and software evolve at a constant pace, and a new computer system design can execute the latest computer software design. However, there are instances in which a new computer system is designed to operate old computer software such as an old operating system. For this reason, new computer designs must maintain backward compatibility with old computer software.
It is known that computer system designers implement a firmware resource on computer system designs that, in a pre-boot environment, initializes a computer system. This firmware resource is known as a basic input output system (BIOS) and is used to provide basic functionality (e.g., display output, keyboard input, disk drive operation, etc.) to a computer system prior to executing an operating system boot process. The BIOS is generally stored on a non-volatile memory device such as a ROM or a flash memory that is designed or integrated into most computer systems.
In recent years, newer firmware resources have been designed that provide functionality similar to the BIOS. One such resource is known as an extensible firmware interface (EFI) that initializes a computer system prior to execution of an operating system boot process. In general, the EFI is targeted toward supporting newer operating systems and application programs. However, for new computer designs to maintain backward compatibility with older or legacy software, the EFI can provide legacy support through compatibility resources known as compatibility support modules. The compatibility support modules are firmware instruction modules that, upon execution, enable a computer system to provide support for legacy computer software, such as legacy operating systems. The compatibility support modules are stored in the ROM or flash memory on which the EFI is stored so that the EFI can unconditionally load the compatibility support module to the computer system prior to executing a software boot process.